Bass (instrument)

From AudioLexic

There are a range of musical instruments that can be collectively regarded as bass instruments since they produce tones that are in the bassrange. They belong to different families of instruments and can cover a wide range of musical roles, often going well beyond simply providing a rhythmic and harmonic foundation for other instruments to build on. What they have in common is that they are the lowest tuned and largest instruments of their respective families.

As seen in the musical instrument classification article, categorizing instruments is far from simple, but examples grouped by general form and playing technique include:

A musician playing one of these instruments is often known as a bassist, certainly in the first two cases, although other terms such as 'bass guitarist', 'double bassist', 'bass player', etc may be used instead.